diff --git a/ihatemoney/forms.py b/ihatemoney/forms.py
index 0e99f534..bbdef334 100644
--- a/ihatemoney/forms.py
+++ b/ihatemoney/forms.py
@@ -247,7 +247,7 @@ class ProjectForm(EditProjectForm):
 
 class ProjectFormWithCaptcha(ProjectForm):
     captcha = StringField(
-        _("Which is a real currency: Euro or Petro dollar?"),
+        _("Which is a real currency: Euro or Petro dollar?"), default=""
     )
 
     def validate_captcha(form, field):